preprint Felix Röhrle author Martin Ulirsch author 114697 A bimatroid is a matroid-like generalization of the collection of regular minors of a matrix. In this article, we use the theory of Lorentzian polynomials to study the logarithmic concavity of natural sequences associated to bimatroids. Bimatroids can be used to characterize morphisms of matroids and this observation (originally due to Kung) allows us to prove a weak version of logarithmic concavity of the number of bases of a morphism of matroids. This is weaker than the original result by Eur and Huh; it nevertheless provides us with a new perspective on Mason's log-concavity conjecture for independent sets of matroids. We finally show that for realizable bimatroids, the regular minor polynomial is a volume polynomial. Applied to morphisms of matroids, this shows that the weak basis generating polynomial of a morphism is a volume polynomial; this confirms a conjecture of Eur--Huh for morphisms of nullity $\leq 1$ and gives an algebro-geometric explanation for Mason's log-concavity conjecture in the realizable case. 2024 eng 2402.15317 Röhrle, F., &#38; Ulirsch, M. (2024). Logarithmic concavity of bimatroids. In <i>arXiv:2402.15317</i>. F. Röhrle and M. Ulirsch, “Logarithmic concavity of bimatroids,” <i>arXiv:2402.15317</i>. 2024. Röhrle, Felix, and Martin Ulirsch. “Logarithmic Concavity of Bimatroids.” <i>ArXiv:2402.15317</i>, 2024. F. Röhrle, M. Ulirsch, ArXiv:2402.15317 (2024). Röhrle, Felix, and Martin Ulirsch. “Logarithmic Concavity of Bimatroids.” <i>ArXiv:2402.15317</i>, 2024. Röhrle F, Ulirsch M. Logarithmic concavity of bimatroids. <i>arXiv:240215317</i>. Published online 2024. @article{Röhrle_Ulirsch_2024, title={Logarithmic concavity of bimatroids}, journal={arXiv:2402.15317}, author={Röhrle, Felix and Ulirsch, Martin}, year={2024} } 663082026-07-08T06:23:01Z2026-07-08T06:23:13Z